During Sol 200, MSL was unable to save data to part of its memory, so the rover stopped what it was doing and waited for more instructions. The engineering team at JPL is analyzing the available telemetry to determine how to recover from this anomaly, and the Sol 201 plan was cancelled. The problem does not sound very serious, but I'm not an engineer and don't know much of the details. As more telemetry is received, the experts will probably figure out what caused the problem and how to avoid it in the future. But for now we have to be patient.